Coating wire drive parts

ABSTRACT

A wire feeding mechanism for advancing a continuous length of wire along a pathway includes a housing having first and second roller supports each rotatable about a corresponding axis transverse to the pathway. A first and second roller supports are on opposite sides of the pathway and are driveably engaged with each other. A first drive roller is on the first roller support for rotation therewith and has a first roller axis coaxial with the axis of the first roller support. The first drive roller has a first drive roller outer surface extending circumferentially about the first axis. A second drive roller is on the second roller support for rotation therewith and has a second roller axis coaxial with the axis of the second roller support. The second drive roller has a second drive roller outer surface extending circumferentially about the second axis. The first and second drive rollers tangentially and compressively contact the continuous length of wire therebetween such that the wire is advanced along the pathway in response to rotation of the drive rollers. At least one wire guide is positioned adjacent the first and second drive rollers and directs the continuous length of wire at least one of (1) into contact with the first and second drive rollers and (2) away from contact with the first and second drive rollers. An anti-friction coating is on at least one of the first drive roller, the second drive roller and the at least one wire guide for reducing deformation and scratching of the continuous length of wire.

BACKGROUND

The present exemplary embodiment relates to the art of wire feeding mechanisms and, more particularly, to drive parts of wire feeding mechanisms used for driveably advancing and guiding a welding wire. It finds particular application as an engineered coating applied to support guides and/or drive rollers of a wire feeding mechanism and will be described with particular reference thereto. It is to be appreciated, however, that the present exemplary embodiment may relate to other similar environments and applications.

U.S. Pat. No. 6,557,742 to Bobeczko et al., U.S. Pat. No. 5,816,466 to Seufer and U.S. Pat. No. 4,235,362 to Hubenko, all expressly incorporated herein by reference, disclose wire feeding mechanisms and provide general background information related thereto.

Wire feeding mechanisms that move consumable electrode wire from a supply reel to a welding gun are generally well known. For example, Seufer discloses a wire feed mechanism having a wire pathway through which a continuous length of wire is advanced. Wire feed mechanisms usually include motor-driven drive rolls that engage diametrically opposite sides of a wire to move the wire along a path through a housing of the feeding mechanism. Once through the housing, the wire is moved through a flexible tube or conduit leading to a welding gun. Often, the conduit also carries shielding gas and electrical current to the welding gun.

Typically, each of the drive rollers is mounted on a roller support and all of the roller supports are driveably engaged with one another. Thus, powered rotation of a single roller support causes rotation of all the roller supports and the drive rollers supported thereon. Usually, the drive rolls are a single pair of opposed rollers or a double pair of opposed rollers spaced apart along the wire path. In either arrangement, the drive rollers have an upstream side at which the wire enters the drive rollers and a downstream side at which the wire exits the driver rollers. On the upstream side, the wire is guided through an upstream wire support guide or tube toward a bite created between the drive rollers adjacent the upstream side. Likewise, on the downstream side, the wire exits the drive rollers and is guided through a downstream wire support guide or tube adjacent the downstream side. If a double pair of opposed rollers are used, another wire support guide or tube can be provided between the pairs of drive rollers to further guide or direct the wire.

To impart an advancing force or motion to the wire, opposing drive rollers are positioned sufficiently close to one another so that the wire extending along the pathway is compressed between the opposing rollers. The compressive force in combination with friction between the material of the wire and the rollers advances the continuous length of wire along the wire path and through the wire support guides in a generally smooth and continuous manner. In some arrangements, one or more of the drive rollers are urged toward the wire by a biasing member to further impart an advancing force or motion on the wire.

The wire passing through the drive rollers has a generally round cross-section and is engaged tangentially by opposing drive rollers mounted transversely to the wire. As a result of this arrangement, the compressive forces exerted on the wire by the driver rollers often cause the wire to undesirably deform. The material characteristics of the wire largely determine the magnitude or amount the wire is deformed as a result of the compressive forces. Accordingly, a wire made from a material having a relatively high compressive yield strength, such as steel, will be deformed less than a wire made from a material having a moderate compressive yield strength, such as aluminum.

In some applications, the drive rollers include U-shaped or V-shaped grooves extending circumferentially thereabout for reducing the deformation of the wire from the compressive forces of the drive rollers. When grooves are employed, the wire is engaged by side walls of the drive rollers forming the grooves. As a result, the compressive forces exerted by each pair of drive rollers act and deform the wire along a substantial portion of the wire's outer surface when U-shaped grooves are used and at four locations when V-shaped grooves are used (two side walls engage the wire on each drive roller) compared to only two locations if no grooves were provided (one circumferential surface of each drive roller would engage the wire). More contact between the drive rollers and the wire results in less deformation. Accordingly, drive rollers having grooves tend to deform the wire to a lesser extent than those without grooves.

Although grooves tend to deform the wire less, grooves can cause other problems including the undesirable build-up of wire residue in the grooves, particularly when aluminum wires are used. Such build-up results in the need for an occasional clean up or removal of the residual wire from the grooves. This is undesirable and any improvement that allows grooves to be used while eliminating or reducing the need to clean out the grooves is considered desirable.

With or without grooves, the surfaces of the drive rollers that contact the wire degrade or wear over extended use. Degradation of the drive roller surfaces results in poor contact between the drive rollers and the wire which can cause slippage between the drive rollers and wire as well as other related problems. It is often costly and time consuming to replace or refurbish the drive rollers on wire feed mechanisms so any improvements to the drive rollers that allow the drive rollers to be used for longer periods without replacement or refurbishment are considered desirable.

One known improvement to drive rollers having grooves is to provide a plurality of grooves on each drive roller. This allows each groove to be used sequentially before the drive roller has to be replaced or refurbished. For example, on a drive roller having two grooves, the first groove can be used until it has sufficiently degraded. Then, the wire can be moved to the second groove and it can be used until degradation. Only after both grooves are worn out does the drive roller need to be replaced or refurbished. Despite this improvement, there is still a need to increase the wear resistance of drive rollers and, thus, any additional improvements that further extend the useful life of drive rollers on wire feed mechanisms are deemed desirable.

SUMMARY

According to one embodiment, a wire feeding mechanism is provided for advancing a continuous length of wire along the pathway. More particularly, in accordance with this embodiment, the wire feeding mechanism includes a housing having first and second roller supports each rotatable about a corresponding axis transverse to the pathway. The first and second roller supports are on opposite sides of the pathway and are driveably engaged with each other. A first drive roller is on the first roller support for rotation therewith and has a first roller axis coaxial with the axis of the first roller support. The first drive roller has a first drive roller outer surface extending circumferentially about the first axis. A second drive roller is on the second roller support for rotation therewith and has a second roller axis coaxial with the axis of the second roller support. The second drive roller has a second drive roller outer surface extending circumferentially about the second axis.

The first and second drive rollers tangentially and compressively contact the continuous length of wire therebetween such that the wire is advanced along the pathway in response to rotation of the drive rollers. At least one wire guide is positioned adjacent the first and second drive rollers and directs the continuous length of wire at least one of (1) into contact with the first and second drive rollers and (2) away from contact with the first and second drive rollers. An anti-friction coating is on at least one of the first drive roller, the second drive roller and the at least one wire guide for reducing deformation and scratching of the continuous length of wire.

In accordance with another embodiment, a wire guide assembly is provided for use on a wire feeding mechanism to guide a continuous length of wire between opposed drive rollers. More particularly, in accordance with this aspect, the wire guide assembly includes a wire guide defining a wire passageway through which the continuous length of wire passes. A smooth coating is on the wire guide and engages the continuous length of wire for facilitating passing of the continuous length of wire by the wire guide.

In accordance with yet another embodiment, a drive roller assembly is provided for use on a wire feeding mechanism to advance a continuous length of wire. More particularly, in accordance with this aspect, the drive roller assembly includes a drive roller having an axis and an outer surface extending circumferentially about the axis. A coating is on the outer surface for tangentially and compressively engaging an associated continuous length of wire.

DESCRIPTION OF THE DRAWINGS

The one or more embodiments may take form in various components and arrangements of components and in various steps and arrangements of steps. The drawings are only for purposes of illustrating the one or more embodiments and are not to be construed as limiting thereof.

FIG. 1 is a schematic view of a wire feeding mechanism having drive rollers and wire guides in accordance with one embodiment.

FIG. 2 is a cross-sectional view of one of the wire guides taken along the line 2-2 of FIG. 1.

FIG. 3 is an elevational view of one of the sets of drive rollers of FIG. 1 with a portion of the drive roller shown in cross-section taken along the line 3-3 of FIG. 2.

FIG. 4 is an elevational view of a set of drive rollers having V-shaped grooves with a portion of the drive rollers shown in cross-section in accordance with an alternate embodiment.

DETAILED DESCRIPTION

With reference now to the drawings wherein the showings are for purposes of illustrating one or more embodiments only and not for purposes of limiting the same, FIG. 1 shows a wire feeding mechanism 10 having a wire pathway 12 defined in part by wire support guides 14,16. The wire feeding mechanism 10 is generally situated between a bulk of wire 18 and a work piece 20. The wire extends from the bulk supply, shown as wheel 22 in FIG. 1, to the wire feeding mechanism 10 and further extends to the work piece 20 where it is consumed in the process of welding. The wire 18 can be alternately supplied in a wide variety of other bulk forms, including for example boxes, reels and the like.

Generally, a flexible conduit 24 extends from the mechanism 10 on a downstream side 26 thereof such that the wire 18 will be advanced by the mechanism 10 through the conduit 24 to a welding gun 28 adjacent the work piece 20. As the mechanism 10 axially advances the wire 18 along the pathway 12, the advancing wire is radially supported and guided by the flexible conduit 24 toward the work piece 20 until the wire 16 reaches the gun 28 and is consumed during the welding process. As is known, the conduit 24 can optionally carry shielding gas and electrical current to the welding gun 28. Alternatively, the flexible conduit 24 can be replaced with a rigid conduit terminating any welding head. In any arrangement, it is to be appreciated that both conduit and welding guns are commonly known and therefore need not be described in further detailed herein.

The wire feeding mechanism 10 includes a housing 30 through which the wire pathway 12 is defined. More particularly, the wire support guides 14,16 are spaced along the wire pathway 12 and are arranged such that passages therethrough are axially aligned along and partially define the pathway 12. The wire feeding mechanism 10 further includes a first set of drive rollers 36,38 and a second set of drive rollers 40,42 disposed along the pathway 12 in spaced relation relative to one another. The drive rollers 36,38,40,42 function to advance the continuous length of wire 18 as will be described in more detail below. More particularly, one drive roller from each pair of drive rollers, drive roller 36 and drive roller 40 in the illustrated embodiment, is disposed on one side of the pathway 12 and the other drive roller from each pair, drive roller 38 and drive roller 42 in the illustrated embodiment, is disposed on the other side of the pathway 12. Each of the rollers 36,38,40,42 is positioned radially adjacent the pathway and tangentially contacts the wire 18. As is known, one or more of the drive rollers 36,38,40,42 can be radially adjustably positionable relative to the wire pathway 12.

On an upstream side of the drive rollers 36,38,40,42, a support guide 14 receives the wire 18 from the wheel 22 and directs the wire into a bite defined between the first set of drive rollers 36,38. On a downstream side of the drive rollers 36,38,40,42, the support guide 16 receives the wire from the second set of drive rollers 40,42 and directs the wire 18 into the conduit 24. A third support guide 44 can be optionally provided between the sets of drive rollers 36,38 and 40,42 to guide the wire 18 from the first set of drive rollers 36,38 into the second set of drive rollers 40,42. The support guides 14,16,44 optionally include tapered interior surfaces to further facilitate guiding of the wire 18.

The first set of drive rollers 36,38 are carried on roller supports 46,48 for rotation therewith. The roller supports 46,48 are rotatably mounted in the housing 30 about respective roller support axes transverse to the wire pathway 12. The drive rollers 36,38 have respective drive roller axes coaxial with the respective roller support axes. Likewise, the second set of drive rollers 40,42 are carried on roller supports 50,52 for rotation therewith. The roller supports 50,52 are rotatably mounted in the housing 30 about respective axes transverse to the wire pathway spaced apart from the first set of drive rollers 36,38. The drive rollers 40,42 have respective drive roller axes coaxial with the respective roller support axes. The roller supports 46,48,50,52 are driveably engaged to one another. Thus, powered rotation of the roller supports 48,52 by a motor M causes rotation of the other roller supports 46,50.

With additional reference to FIG. 2, the wire guide support 14 includes a base member 60 and a cap or lid member 62. The base member 60 defines a groove 64 that receives the wire 18. A threaded member 66 secures the cap 62 to the base member 60 and secures the base member and cap 60,62. to the housing 30. More particularly, the threaded member 66 includes threads 68 threadedly engaged to the housing 30. The threaded member 64 further includes a head 70 that holds the lid member 62 against the base member 60. The wire support guide 14 additionally includes an anti-friction coating along portions thereof for engaging the wire 18 and reducing deformation and scratching of the wire 18. More specifically, the anti-friction coating includes a first portion 72 received along the groove 64 for contacting the wire 18. A second portion 74 of the anti-friction coating is disposed along an abutting edge 72 of the lid member 62 thereby sandwiching the wire 18 between the portions 68,70 of the anti-friction coating. Of course, other coating arrangements are possible and are to be considered well within the scope of the invention. For example, the anti-friction coating can only be provided on one of the groove 64 and the lid 62 and/or can be provided along the surface of the base member 60 that abuts the lid 62, etc.

In one embodiment, the anti-friction coating is an engineered material that is smooth and has a low coefficient of friction. For this purpose, the engineered material can be one of plastic and ceramic. For example, when the engineered material is plastic it can be one of fluorocarbon, nylon, acetal, graphite-filled epoxy and polyethylene and when the engineered material is ceramic, it can be one of alumina, diamond, alumina nitride, titanium dioxide, ganutrium and zirconia. The base member 60 and the lid member 62 to which the anti-friction coating is applied are constructed or composed of a metallic alloy and, preferably, formed of hardened steel. According to one embodiment, the anti-friction coating is up to about 0.030 inches (0.762 millimeters) thick and, preferably, the anti-friction coating is about 0.03 inches (0.762 millimeters) thick.

The wire support guide can further include a guidepost 76 mounted within the base member 60 and received within a recess or aperture 78 of the lid member 62. The guide post 76 functions to prevent relative rotation of the lid member 62 on the base member 60. Although only a single post 76 is shown in the illustrated embodiment, it should be appreciated that any number of additional posts could be provided.

With additional reference to FIG. 3, each of the drive rollers 36,38,40,42 (only drive rollers 36,38 shown in FIG. 3) includes a hub 80 having an outer surface 82 extending circumferentially about the corresponding drive roller axis and an anti-friction coating 84 on the outer surface 82 extending circumferentially about the outer surface in the corresponding drive roller axis. Like the anti-friction coating on the guide 14, the anti-friction coating 84 on the drive rollers reduces deformation and scratching of the wire 18 when in contact with the drive rollers.

In one embodiment, the anti-friction coating 84 is an engineered material that is smooth and has a low coefficient of friction. For this purpose, the engineered material can be one of plastic and ceramic. As an example, when the engineered material 84 is plastic, it can be one of fluorocarbon, nylon, acetal, graphite-filled epoxy and polyethylene. When the engineered material is ceramic, it can be one of alumina, diamond, alumina nitride, titanium dioxide, ganutrium and zirconia. Similar to the base and lid members 60,62, the hubs 80 are composed of a metallic alloy and, preferably, formed of hardened steel. In a preferred embodiment, the anti-friction coating 84 is up to about 0.03 inches (0.762 millimeter) thick and, preferably, is about 0.030 inches (0.762 millimeter) thick.

On either the drive rollers or the wire guides, the anti-friction coating reduces deformation and scratching of the wire 18, particularly when the wire 18 is a soft wire, such as aluminum. Moreover, it has been found that the anti-friction coating reduces the likelihood of the wire 18 “birdnesting” in the event of a feeding problem. Reduction of such an occurrence reduces the likelihood that the parts, such as the drive rollers and the wire guides, are damaged. Thus, the anti-friction coating on these parts protects soft wires, such as those made from aluminum, from damage while generally being impervious to damage caused by “birdnesting.”

To impart an advancing force or motion to the wire 18, opposing sets of drive rollers 36,38 and 40,42 are positioned sufficiently close to one another so that the wire 18 extending along the pathway 12 is compressed between the rollers 36,38,40,42. More specifically, the anti-friction coating 84 on the drive rollers 36,38,40,42 tangentially and compressively contacts the wire 18. The compressive force in combination with friction between the wire 18 and the rollers 36,38,40,42 advances the continuous length of wire 18 along the wire path 12 in a generally smooth and continuous manner. Optionally, one or more of the drive rollers 36,38,40,42 can be urged toward or into the wire 18 to further impart an advancing force or motion on or to the wire 18 when the rollers are rotating. In one embodiment, the drive rollers 36,38,40,42 include radial grooves 90 for receiving the wire 18. The radial grooves 90 are defined in the outer surface 82 of each of the drive rollers and the coating 84 is provided on the outer surface 82 and in the radial grooves 90.

With reference to FIG. 4, the drive rollers 36′,38′ are shown in accordance with an alternate preferred embodiment. There, like components are identified by like numerals with a primed (′) suffix for ease of appreciating this alternative arrangement. The drive rollers 36′,38′ mounted on roller supports 46′,48′ include V-shaped grooves 92 defined by angled sidewalls 94,96 in outer surface 82′ of hubs 80′. The V-shaped grooves 92 extend circumferentially about the drive rollers 36′,38′ and serve to reduce deformation of wire 18′ caused by compressive forces of the drive rollers 36′,38′. More particularly, the wire 18′ is engaged by the sidewalls 94,96. As a result, the compressive force is exerted by each pair of drive rollers 36′,38′ and 40′,42′ acting to deform the wire 18 at four contact locations.

In FIGS. 3 and 4, the drive rollers (36,38 in FIG. 3 and 36′,38′ in FIG. 4) each include a pair of grooves. One of the grooves on each drive roller can be used until its defining surfaces have degraded to a sufficient extent. Then, the wire can be moved to the second of the grooves. Only after both grooves are worn out might the drive roller need to be replaced or refurbished. Alternatively, the pair of grooves can be sized differently for accommodating wires of varying diameters.

The exemplary embodiment has been described with reference to one or more embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the exemplary embodiment be construed as including all such modifications and alterations insofar as they are within the scope of the appended claims and the equivalents thereof. 

1. A wire feeding mechanism for advancing a continuous length of wire along a pathway, said wire feeding mechanism comprising: a housing having first and second roller supports each rotatable about a corresponding axis transverse to said pathway, said first and second roller supports being on opposite sides of said pathway and being driveably engaged with each other; a first drive roller on said first roller support for rotation therewith and having a first roller axis coaxial with the axis of the first roller support, said first drive roller having a first drive roller outer surface extending circumferentially about said first axis; a second drive roller on said second roller support for rotation therewith and having a second roller axis coaxial with the axis of the second roller support, said second drive roller having a second drive roller outer surface extending circumferentially about said second axis, said first and second drive rollers tangentially and compressively contacting said continuous length of wire therebetween such that said wire is advanced along said pathway in response to rotation of said drive rollers; at least one wire guide positioned adjacent said first and second drive rollers and directing said continuous length of wire at least one of (1) into contact with said first and second drive rollers and (2) away from contact with said first and second drive rollers; and an anti-friction coating on at least one of said first drive roller, said second drive roller and said at least one wire guide for reducing deformation and scratching of said continuous length of wire.
 2. The wire feeding mechanism of claim 1, wherein said anti-friction coating is an engineered material that is smooth and has a low coefficient of friction.
 3. The wire feeding mechanism of claim 2, wherein said engineered material is one of plastic and ceramic.
 4. The wire feeding mechanism of claim 3, wherein said engineered material is one of fluorocarbon, nylon, acetal, graphite-filled epoxy and polyethylene.
 5. The wire feeding mechanism of claim 3, wherein said engineered material is one of alumina, diamond, alumina nitride, titanium dioxide, ganutrium and zirconia.
 6. The wire feeding mechanism of claim 1, wherein said at least one of said first drive roller, said second driver roller and said at least one wire guide is composed of a metallic alloy.
 7. The wire feeding mechanism of claim 6, wherein said at least one of said first driver roller, said second driver roller and said at least one wire guide is formed of hardened steel.
 8. The wire feeding mechanism of claim 1, wherein said anti-friction coating is up to about 0.030 inches (0.762 mm) thick.
 9. The wire feeding mechanism of claim 8, wherein said anit-friction coating is about 0.030 inches (0.762 mm) thick.
 10. The wire feeding mechanism of claim 1, wherein at least one of the first and second driver rollers is radially adjustably positionable relative to said pathway.
 11. A wire guide assembly for use on a wire feeding mechanism to guide a continuous length of wire between opposed drive rollers, the wire guide assembly comprising: a wire guide defining a wire passageway through which said continuous length of wire passes; and a smooth coating on said wire guide and engaging said continuous length of wire for facilitating passing of said continuous length of wire by said wire guide.
 12. The wire guide assembly according to claim 11, wherein said wire guide is made of hardened steel.
 13. The wire guide assembly according to claim 11, wherein said coating is an engineered material having a low coefficient of friction.
 14. The wire guide assembly according to claim 13, wherein said engineered material is one of plastic and ceramic.
 15. The wire guide assembly according to claim 14, wherein said engineered material is one of fluorocarbon, nylon, acetal, graphite-filled epoxy, polyethylene, alumina, diamond, alumina nitride, titanium dioxide, ganutrium and zirconia.
 16. The wire guide assembly according to claim 11, wherein said coating is up to about 0.030 inches (0.762 mm) thick.
 17. A drive roller assembly for use on a wire feeding mechanism to advance a continuous length of wire, said drive roller assembly comprising: a drive roller having an axis and an outer surface extending circumferentially about said axis; and a coating on said outer surface for tangentially and compressively engaging an associated continuous length of wire.
 18. The drive roller assembly of claim 17, wherein said drive roller is formed of hardened steel.
 19. The drive roller assembly of claim 17, wherein said coating is an engineered material having a relatively low coefficient of friction.
 20. The drive roller assembly of claim 19, wherein said engineered material is one of plastic and ceramic.
 21. The drive roller assembly of claim 20, wherein said coating is approximately 0.030 inches (0.762 mm) thick. 